notice the little dings in it? Bet you could get that by bracing the hood with sand or something not solid, but sturdy and then throw gravel on it. Test in an inconspicuious spot first to see how to get the desired look, then go get a metal antiquing treatment like they sell at hardware or craft stores. It's going to be similar to the kind used to get patina on copper.

The treatment on the hood is done by Liquid Metal Coatings, Inc. You can look on thier website for their technique: http://www.liquidmetalcoatings.com/ Its a very custom artistic process.